How to use Zend Framework Form Hash (token) with AJAX

Question

I have included Zend_Form_Element_Hash into a form multiplecheckbox form. I have jQuery set to fire off an AJAX request when a checkbox is clicked, I pass the token with this AJAX request. The first AJAX request works great, but the subsequent ones fail.

I suspect it may be once the token has been validated it is then removed from the session (hop = 1).

What would be your plan of attack for securing a form with Zend Framework Hash yet using AJAX to complete some of these requests?

Carsoncarstensz

Answer 1

I finally abandoned using Zend_Form_Element_Hash and just created a token manually, registered it with Zend_Session and then checked it upon submission.

form.php

$myNamespace = new Zend_Session_Namespace('authtoken');
$myNamespace->setExpirationSeconds(900);
$myNamespace->authtoken = $hash = md5(uniqid(rand(),1));
$auth = new Zend_Form_Element_Hidden('authtoken');
$auth->setValue($hash)
     ->setRequired('true')
     ->removeDecorator('HtmlTag')
     ->removeDecorator('Label');    

controller.php

$mysession = new Zend_Session_Namespace('authtoken');
$hash = $mysession->authtoken;
if($hash == $data['authtoken']){
    print "success";
} else {
    print "you fail";
}

This seems to work and still keeps things relatively sane and secure. I'd still rather use the Hash element, but I can't seem to make it work with AJAX.

Thanks all.

Carsoncarstensz

Answer 2

That's how to handled hash field in ajax form :

class AuthController extends Zend_Controller_Action
{
    public function init()
    {
        $contextSwitch = $this->_helper->getHelper('contextSwitch');
        $contextSwitch->addActionContext('index', 'json')
                      ->initContext();
    }

    public function loginAction()
    {
        $form = new Application_Form_Login();
        $request = $this->getRequest();

        if ($request->isPost()) {
            if ($form->isValid($request->getPost())) {
                // some code ..
            } else {
                // some code ..

                // Regenerate the hash and assign to the view
                $reservationForm->hash->initCsrfToken();
                $this->view->hash = $reservationForm->hash->getValue();
            }
        }
        $this->view->form = $form;
    }
}

And then in your view script ..

<? $this->dojo()->enable()
                ->requireModule('dojox.json.query')
                ->onLoadCaptureStart() ?>
function() {
    var form = dojo.byId("login_form")
    dojo.connect(form, "onsubmit", function(event) {
        dojo.stopEvent(event);

        var xhrArgs = {
            form: this,
            handleAs: "json",
            load: function(data) {
                // assign the new hash to the field
                dojo.byId("hash").value = dojox.json.query("$.hash", data);

                // some code ..
            },
            error: function(error) {
                // some code ..
            }
        }
        var deferred = dojo.xhrPost(xhrArgs);
    });
}
<? $this->dojo()->onLoadCaptureEnd() ?>

Hope it's not too late :D

Mythopoeic

The important part here is to call $hashElement->initCsrfToken(); before getting the value. – Absently

Answer 3

There is a solution:

Create, besides the form that will contain the data, a form without elements. From the controller you instantiate the two forms. Also in the controller, you add the element hash to the empty form. Both forms should be sent to the vision. Then, in the condition "if ($ request-> isXmlHttpRequest ())" in the controller you render the empty form. Then, you take the hash value with the method "getValue ()". This value must be sent in response by Ajax and then use JavaScript to replace the hash value that is already obsolete. The option to create an empty form for the hash is to avoid problems with other elements such as captcha that would have its id generated again if the form were rendered, and would also need to have the new information replaced. The validation will be done separately because there are two distinct forms. Later you can reuse the hash (empty) form whenever you want. The following are examples of the code.

//In the controller, after instantiating the empty form you add the Hash element to it:
$hash = new Zend_Form_Element_Hash('no_csrf_foo');
$hash_form->addElement('hash', 'no_csrf_foo', array('salt' => 'unique'));

 //...

//Also in the controller, within the condition "if ($request->isXmlHttpRequest())" you render the form (this will renew the session for the next attempt to send the form) and get the new id value:
$hash_form->render($this->view);
$hash_value['hash'] = $hash_form->getElement('no_csrf_foo')->getValue();//The value must be added to the ajax response in JSON, for example. One can use the methods Zend_Json::decode($response) and Zend_Json::encode($array) for conversions between PHP array and JSON.

//---------------------------------------

//In JavaScript, the Ajax response function:
document.getElementById("no_csrf_foo").value = data.hash;//Retrieves the hash value from the Json response and set it to the hash input.

Leo

Superintendency

Answer 4

Form hashes are great in principle and a bit of a nightmare in practice. I think the best way to handle this is to return the new hash with the response when you make a request, and update the form markup or store in memory for your javascript as appropriate.

The new hash may be available from the form object, or you can read it from the session.

Kain

I'm already get new token value from my class Form and the token value already changed after request ajax but my token still expired <input type="hidden" id="token" value="799a62c2613085942f4036df0d220eb2" name="token"> – Yetta

Answer 5

You hinted at the right answer in your question: increase the hop count.

There was specific mention of this in the ZF manual online, but they updated their manuals and now i can't find it (grin)- otherwise i would have posted the link for you.

Potiche

Can confirm this does work, but I'm not sure how it affects the effectiveness of the CSRF check overall. One note is that I extended the element myself and created my own, overwriting the initCsrfToken() method - don't edit the Zend files directly – Temple

Answer 6

If you want to use form validator in ajax side use following code :

Myform.php

class Application_Form_Myform extends Zend_Form
{ 
    # init function & ... 
    public function generateform($nohash = false)
    { 
        # Some elements
        if(!$nohash)
        {
           $temp_csrf = new Zend_Session_Namespace('temp_csrf'); 
           $my_hash = new Zend_Form_Element_Hash ( 'my_hash' );
           $this->addElement ( $my_hash , 'my_hash');  
           $temp_csrf->hash = $my_hash->getHash();
        }
        # Some other elements
    }
}

AjaxController.php

class AjaxController extends Zend_Controller_Action
{ 
    // init ... 
    public function validateAction()
    { 
         # ... 
         $temp_csrf = new Zend_Session_Namespace('temp_csrf');
         if($temp_csrf->hash == $params['received_hash_from_client'])
         {
             $Myform     = new Application_Form_Myform(); 
             $Myform->generateform(true);
             if($AF_Bill->isValid($params))
             {
                 # Form data is valid
             }else{
                 # Form invalid
             }
         }else{
             # Received hash from client is not valid
         }
         # ... 
    }
}

Slog